Processing method of forming a concavity in a pipe member and an apparatus thereof

ABSTRACT

Provided are a processing method of forming a concavity in a pipe member and an apparatus thereof, which allows to form a concavity in a pipe member with little shear droop produced in a corner portion of the concavity. According to the present invention, a plurality of rollers, each having similar shape and made of same material, is sequentially brought into contact with and pressed to the same site of processing on a pipe member to thereby deform that site. The quantity of deformation of the pipe is increased step by step, and finally the concavity of desired shape may be formed. The shear droop in a corner portion of thus formed concavity can be minimized since the quantity of deformation by each roller is controlled to be small and a plurality of processing operations is applied.

BACKGROUND OF THE INVENTION

The present invention generally relates to a processing method of forming a concavity in a pipe member and an apparatus thereof, and in particular to a processing method of forming a concavity in a pipe member made of metal and an apparatus thereof, which allows to form a concavity in the pipe member with little shear droop.

To form a concavity in a predetermined location of a pipe member made of metal, conventionally a press machine has been used, for example. Specifically, in said conventional manner, the pipe member is secured by using an upper die and a lower die, and then a punch is activated to apply a pressure against the predetermined location on an outer surface of the pipe member thus to collapse that specified portion.

FIG. 5 illustrates a concept of the above-mentioned processing method. In the drawing, FIG. 5(A) shows a cross-sectional view including an axial line of the pipe member, and FIG. 5(B) shows another cross sectional view orthogonal to the axial line. Reference numeral 51 designates a pipe member made of metal and 52 designates a concavity formed thereon, respectively. The punch 53 is driven in the direction orthogonal to the axial line of the pipe member 51 to form the concavity 52 having a predetermined shape on its contact surface side.

However, in such a conventional method of processing the pipe members, due to a hitting operation with the punch against the site to be processed at a predetermined velocity, a large shear droop “S” has often been formed in a corner portion of the processed site (i.e., a periphery of the concavity) 52. Additionally, it has been required to control the driving velocity and the stroke of the punch in a sophisticated manner in order to improve a percentage of non-defective products with respect to the total quantity thereof.

SUMMERY OF THE INVENTION

Accordingly, an object of the present invention is to provide a processing method of forming a concavity in a pipe member and an apparatus thereof, which may hardly allow the shear droop to be produced in a corner portion of a resulting concavity or allow only a small shear droop if any. A further object of the present invention is to provide a processing method of forming a concavity in a pipe member and an apparatus thereof, which may facilitate a control for driving members used for processing operations.

According to a first aspect of the present invention, provided is a processing method of forming a concavity in a pipe member, comprising the steps of: pressing a first roller moving linearly within a plane orthogonal to an axial line of a pipe member while rotating on its own axis, against an outer surface of the fixedly secured pipe member to thereby form a concavity in a site of contact on said pipe member; and subsequently, pressing a second roller having the same shape as said first roller and also moving linearly within said orthogonal plane while rotating on its own axis, against the same site as said site of contact to thereby increase a dimension of said concavity so as to form the concavity of desired shape in said site of contact on said pipe member.

According to a second aspect of the present invention, provided is a processing method of forming a concavity in a pipe member, comprising the steps of: pressing a first roller having substantially cylindrical shape and moving within a plane orthogonal to an axial line of a pipe member while rotating on its own axis, against an outer surface of the fixedly secured pipe member to thereby form in a site of contact on said pipe member a concavity having a side wall defined by a planar surface orthogonal to the axial line of said pipe member; and subsequently, pressing a second roller having the same shape as said first roller and also moving within said orthogonal plane while rotating on its own axis, against the same site as said site of contact to thereby increase a dimension of said concavity so as to form the concavity having the side wall of desired height defined by the planar surface orthogonal to the axial line of said pipe member in said site of contact on said pipe member.

In this case, the roller may be driven by a motor or may be rotatably supported by a pivot.

According to a third aspect of the present invention, provided is a processing method of forming a concavity in a pipe member, in which a movable member is moved close to and away from a pipe member, which has been fixedly secured to a stationary member, within a plane orthogonal to an axial line of said pipe member such that a plurality of similarly configured rollers, each having substantially cylindrical shape and rotatably supported by said movable member, may be pressed against one and the same site of said pipe member in a sequential manner so as to form in the site of pressing on said pipe member a concavity having a side wall of desired height defined by a planar surface orthogonal to said axial line of said pipe member, wherein among said plurality of rollers, as compared to a first roller that is firstly pressed against the specified site on the pipe member, a subsequent roller to be applied subsequently to the same site will be pressed toward a location of said pipe member closer to said axial line thereof than that for the first roller.

According to the method described above, the pipe member is fixedly secured, and a plurality of similarly configured rollers, each having substantially cylindrical shape and capable of rotating freely, is pressed against the site to be processed in the fixedly secured pipe member. The moving direction of the roller is orthogonal to the axial line of the pipe member. The pressing operation by those rollers is applied more than one time. Consequently, a quantity of deformation of the concavity in the pipe member produced by the multiple times of pressing operations by the rollers can be increased step by step. As a result, a concavity having a desired shape and depth may be formed in the site of processing in the pipe member.

According to the present invention, there will be less possibility for the shear droop to be produced in a corner portion of the resultant concavity in the pipe member. Otherwise, if any, a degree of the shear droop will be extremely smaller as compared to that by the prior art method. Consequently, non-defective products processed with high precision can be obtained. Further, since the rollers capable of rotating freely have been employed as the processing jigs, its durability could be enhanced and the running cost thereof could be improved as compared with the conventional method. Further, driving and rotating of a plurality of rollers may help ensure high precision of the processing, which may satisfy any requirements for respective specified material.

According to a fourth aspect of the present invention, provided is a processing apparatus of forming a concavity in a pipe member, comprising: a stationary member for fixedly securing a pipe member; a first roller of substantially cylindrical shape, which is moved with respect to said fixedly secured pipe member within a plane orthogonal to an axial line thereof so as to be pressed against an outer surface of said pipe member while rotating on its own axis to thereby form in the site of contact on said pipe member a concavity having a side wall defined by a planar surface orthogonal to the axial line of said pipe member; and a second roller configured into the same shape as said first roller, which is moved within said orthogonal plane so as to be pressed against the same site on said pipe member as said site of contact by said first roller while rotating on its own axis and to increase a dimension of said concavity to thereby form in said site of contact on said pipe member a concavity having a side wall of desired height defined by the planar surface orthogonal to the axial line of said pipe member.

According to a fifth aspect of the present invention, provided is a processing apparatus of forming a concavity in a pipe member, comprising: a stationary member for fixedly securing a pipe member; a movable member which is moved close to and away from said pipe member fixedly secured to said stationary member within a plane orthogonal to an axial line of said pipe member; and a plurality of similarly configured rollers, each having substantially cylindrical shape and supported rotatably by said movable member, which are pressed against one and the same location of said pipe member fixedly secured to said stationary member in a sequential manner as a result of said close-to and away-from motion of said movable member to thereby form in the site of pressing on said pipe member a concavity having a side wall of desired height defined by a planar surface orthogonal to the axial line of said pipe member.

According to a sixth aspect of the present invention, provided is a processing apparatus of forming a concavity in a pipe member, in which said plurality of rollers is installed in said movable member in such a manner that a distance between an axial line of each roller of said plurality of similarly configured rollers and the axial line of said pipe member measured in said site of pressing is set to be longest for a first roller to be firstly pressed against said site and the distance for the subsequent rollers to be pressed subsequently are reduced step by step in sequence.

In the above-described invention, a plurality of similarly configured rollers of substantially cylindrical shape are brought into contact with the same location on the outer surface of the pipe member in a sequential manner. In this case, the rollers are moved in the direction orthogonal to the axial line of the pipe member to come into contact therewith. In this regard, for example, the distance between the axial line of each of said rollers and the axial line of the pipe member in this contact position has been set to be longest with respect to the first roller coming into contact with the pipe member firstly and to be shorter step by step sequentially with respect to the subsequent rollers coming into contact with the pipe member subsequently. As a result, the concavity of desired shape will be formed in the contact location of the pipe member. Further, installing a plurality of rollers in the movable member to be supported thereon can help facilitate the forming of concavity efficiently.

Since a plurality of rollers is employed, a load to be applied to each roller during the pressing operation may be reduced as compared to the case of the single roller and thereby the durability thereof will be improved.

Further, since the plurality of rollers is moved in the direction orthogonal to the axial line to come into contact with the pipe member, the concavity can be successfully formed with high precision in the desired location in an efficient manner. It is to be noted that the movement of the rollers is not limited to only one direction but the rollers may make a reciprocating motion in this tangential direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for illustrating a processing method of forming a concavity in a pipe member according to a first embodiment of the present invention;

FIG. 2 is a sectional view of a concavity formed by the processing method according to the first embodiment of the present invention;

FIG. 3 is an exploded perspective view showing main components of an apparatus used in the processing method according to the first embodiment of the present invention;

FIG. 4 is an elevational view showing main components of an apparatus used in the processing method for forming a concavity according to an alternative embodiment of the present invention; and

FIG. 5 is a sectional view showing a resultant concavity formed in the processing method according to the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will now be described with reference to FIGS. 1 to 3. FIG. 1 shows a concept of this processing method according to the present invention. FIG. 2 shows a site of processing in a pipe member in a sectional view. FIG. 3 shows a schematic diagram of an apparatus used in the processing method.

As shown in FIG. 3, first of all, a pipe member 11 made of metal is secured between an upper die 12 and a lower die 13. The lower die 13 made of metal is fixedly installed at a predetermined height level, and the upper die 12 also made of metal is arranged above and in an opposite location with respect to this lower die 13 so as to be moved close to and away from the lower die 13 freely. A set of concavity portions 12A and another set of concavity portions 13A, each having predetermined shape, are formed in the predetermined locations in a lower surface of the upper die 12 and an upper surface of the lower die 13 respectively such that each pair of concavities 12A and 12B may be formed in the corresponding locations in plan view. Further, the upper die 12 and the lower die 13 are made of block of rectangular parallelepiped shape and rectangular holes 12B and 13B having similar shape with each other are formed penetrating through central locations thereof in the up and down direction respectively. Said set of concavity portions 12A, 13A is formed in a side wall (in the inner wall) on one side of the hole 12B, 13B respectively. Consequently, said set of concavity portions 12A, 13A defines four channels having semi-circular sections extending in the up and down directions.

A plurality of rollers 14, 15, 16, 17 and 18, all of which are made of the same material and formed into the same complement shapes with respect to the set of concavity portions 12A, 13A, is pivotally mounted in a movable member 19 so as to rotate freely. Specifically, this five-step of rollers 14-18 are sequentially brought into contact with the same site of processing (in the outer surface) of the secured pipe member 11 so as to press and deform the site of processing, thereby forming the concavity 20 of desired shape in said site of processing. The material of the pipe member 11 in this case may be steel, aluminium, brass and other kinds of alloys. A thickness thereof may be varied arbitrarily.

Specifically, the movable member 19 is operatively installed such that it may be moved up and down freely at a specified velocity through the rectangular holes 12B and 13B of the upper die 12 and the lower die 13.

During said pressing and deforming operation, the rollers are pivotally supported in the movable member 19 such that the distances of the axial lines of respective rollers 14-18 from the axial line of the pipe member 11 may vary from each other. In specific, as illustrated in FIG. 1, in comparison with a center distance “a” for the firstly contacting roller 14 (a distance between a center of the secured pipe member and an axial center of the roller on the movable member measured in a direction orthogonal to the moving direction of the movable member), a center distance “b” for the subsequently contacting roller 15 is shorter Further, as compared to the center distance “b” between the roller 15 and the pipe member 11, a center distance “c” for the thirdly contacting roller 16 is shorter. The center distances for the fourth and the fifth rollers may become sequentially shorter. In this way, the distances are set to be shorter step by step in a sequence of contact. A difference between distances (a-b, b-c, . . . ) in this operation may be or may not be constant. Resultantly, the pipe member 11 in the site of processing is pressed and deformed by respective rollers and a quantity of pressing and deforming in this operation (a quantity of concavity deformation) is increased step by step, and finally it reaches the concavity 20 of desired shape and depth.

In other words, the rollers 14-18 are rotatably supported in the movable member 19, have similar size and shape and are made of same material, but are different in respective dimensions protruding from a front face of the movable member 19 (the protrusions for the rollers located in the middle and lower rows are relatively smaller). As the material of the rollers 14-18, hard material such as SKD material and height speed steel may be employed. Further, the roller is formed into a cylindrical shape as a whole with a tapered portion in one end of the axial line. As for the shape of the roller, additionally, a completely circular cylinder shape or a barrel shape may be employed.

It is to be noted that the movable member 19 is configured to move linearly in the tangential direction with respect to said pipe member 11 and the movement is carried out at a specified speed. A driving mechanism for the movable member 19 may employ such a known mechanism including a cylinder. Further, in this embodiment, the concavities 20 of similar shape can be formed concurrently in four different locations spaced equally in the longitudinal direction along the outer surface of the pipe member 11. To this end, four rollers are arranged in the abacus form as a whole in the direction normal to the moving direction of the movable member 19. Further, during said processing, a coolant (e.g., water) may be supplied to the site of processing. This may be effective especially in a high speed processing.

FIG. 2 shows a sectional view of the concavity 20 formed by the above-described method. This concavity 20 has been formed in accordance with the shape of the rollers and has a side wall in one end side extending perpendicularly, a horizontal bottom wall and another side wall in the other end side having been tapered at a specified angle. This concavity 20 will not exhibit any shear droop in a corner portion thereof (or small shear droop, if any). The reason for this is because the quantity of deformation by each roller is limited to be small and a plurality of deforming processes is applied to accomplish a desired deforming operation.

FIG. 4 shows an alternative embodiment of the present invention. In this embodiment, each of the rollers 21, 22 and 23 having similar shapes and made of same material is adapted to be driven by a motor at a specified rotational speed. Specifically, in this configuration, a turning force is sequentially transmitted in the following manner: from a gear 24 mounted on an output shaft end of a driving motor to a gear 21A of a first roller, from this gear 21A via an intermediate gear 25 to a gear 22A of a second roller, and further from the gear 22A via an intermediate gear 26 to a gear 23A of a third roller. Those rollers and respective gears are mounted on a casing movable in the up and down direction, though not shown.

Since the intermediate gears 25 and 26 are rotatably interposed between respective roller gears, each roller 21, 22 and 23 can rotate in the same direction. Accordingly, each roller can be driven at a constant rotational speed and in the same direction all the time. Further, the rotational speed can be modified accordingly based on the material or the expected quantity of deformation of the pipe. Further, the rotational direction may be in conformity to the moving direction of the roller or may be reversed. This enables a processing with higher precision. Other configurations are similar to those in the first embodiment. In the drawing, “W” designates a distance between the rotational centers of respective rollers (corresponding to the quantity of deformation in the concavity). This distance may be constant or may be varied.

It is to be noted that the present invention has been described in conjunction with a concavity processing for a pipe member to be used, for example, in a chair, only by way of example, and the present invention is not limited to this. For example, this concavity processing may be applicable to a rack having gears formed therein.

Further, the shape of the concavity is also not limited to that described in the above embodiment but may be formed into a variety of shapes in processing. For example, the concavity having a U-shaped section or having tapered lines in both sides may be contemplated. In those cases, the shape of the roller may be modified from the original cylindrical shape with one-side tapered to the correspondingly desired shapes. 

1. A processing method of forming a concavity in a pipe member, comprising the steps of: pressing a first roller moving linearly within a plane orthogonal to an axial line of a pipe member while rotating on its own axis, against an outer surface of the fixedly secured pipe member to thereby form a concavity in a site of contact on said pipe member; and subsequently, pressing a second roller having the same shape as said first roller and also moving linearly within said orthogonal plane while rotating on its own axis, against the same site as said site of contact to thereby increase a dimension of said concavity so as to form the concavity of desired shape in said site of contact on said pipe member.
 2. A processing method of forming a concavity in a pipe member, comprising the steps of: pressing a first roller having substantially cylindrical shape and moving within a plane orthogonal to an axial line of a pipe member while rotating on its own axis, against an outer surface of the fixedly secured pipe member to thereby form in a site of contact on said pipe member a concavity having a side wall defined by a planar surface orthogonal to the axial line of said pipe member; and subsequently, pressing a second roller having the same shape as said first roller and moving within said orthogonal plane while rotating on its own axis, against the same site as said site of contact to thereby increase a dimension of said concavity so as to form the concavity having the side wall of desired height defined by the planar surface orthogonal to the axial line of said pipe member in said site of contact on said pipe member.
 3. A processing method of forming a concavity in a pipe member, in which a movable member is moved close to and away from a pipe member, which has been fixedly secured to a stationary member, within a plane orthogonal to an axial line of said pipe member such that a plurality of similarly configured rollers, each having substantially cylindrical shape and rotatably supported by said movable member, may be pressed against one and the same site of said pipe member in a sequential manner so as to form in the site of pressing on said pipe member a concavity having a side wall of desired height defined by a planar surface orthogonal to said axial line of said pipe member, wherein among said plurality of rollers, as compared to a first roller that is firstly pressed against the specified site on the pipe member, a subsequent roller to be applied subsequently to the same site will be pressed toward a location of said pipe member closer to said axial line thereof than that for the first roller.
 4. A processing apparatus of forming a concavity in a pipe member, comprising: a stationary member for fixedly securing a pipe member; a first roller of substantially cylindrical shape, which is moved with respect to said fixedly secured pipe member within a plane orthogonal to an axial line thereof so as to be pressed against an outer surface of said pipe member while rotating on its own axis to thereby form in the site of contact on said pipe member a concavity having a side wall defined by a planar surface orthogonal to the axial line of said pipe member; and a second roller configured into the same shape as said first roller, which is moved within said orthogonal plane so as to be pressed against the same site on said pipe member as said site of contact by said first roller while rotating on its own axis and to increase a dimension of said concavity to thereby form in said site of contact on said pipe member a concavity having a side wall of desired height defined by the planar surface orthogonal to the axial line of said pipe member.
 5. A processing apparatus of forming a concavity in a pipe member, comprising: a stationary member for fixedly securing a pipe member; a movable member which is moved close to and away from said pipe member fixedly secured to said stationary member within a plane orthogonal to an axial line of said pipe member; and a plurality of similarly configured rollers, each having substantially cylindrical shape and supported rotatably by said movable member, which are pressed against one and the same location of said pipe member fixedly secured to said stationary member in a sequential manner as a result of said close-to and away-from motion of said movable member to thereby form in the site of pressing on said pipe member a concavity having a side wall of desired height defined by a planar surface orthogonal to the axial line of said pipe member.
 6. A processing apparatus of forming a concavity in a pipe member in accordance with claim 5, in which said plurality of rollers is installed in said movable member in such a manner that a distance between an axial line of each roller of said plurality of similarly configured rollers and the axial line of said pipe member measured in said site of pressing is set to be longest for a first roller to be firstly pressed against said site and the distance for the subsequent rollers to be pressed subsequently are reduced step by step in sequence. 